People with type 2 diabetes are often prescribed drugs to boost their production of insulin. The controversial belief that these so-called sulfonylurea drugs increase mortality in patients with diabetes now gets support from a new study by researchers in Canada.

A 1970 report suggested a link between sulfonylureas and cardiovascular events, but since then other studies have refuted this association and the drugs have remained a mainstay of diabetes therapy.

Previously, Dr. Scot H. Simpson and colleagues had shown that metformin, another type of anti-diabetes drug that works by increasing the body’s response to insulin, confers a survival advantage over the sulfonylureas.

Still, it was unclear if this was due to a protective effect of metformin or from a potentially adverse effect from the sulfonylureas.

To investigate, Simpson’s team from the University of Alberta in Edmonton analyzed data for 5795 subjects who were prescribed an oral anti-diabetic drug and were entered in the Saskatchewan Health databases between 1991 and1999.

As reported in the Canadian Medical Association Journal, at higher daily doses sulfonylurea-type drugs were associated with an increased risk of death, but this was not seen with metformin.

“Clinicians should carefully assess the need for sulfonylurea therapy in subjects at high risk of cardiovascular events - particularly now, when several other classes of antidiabetic oral medications are available,” the investigators conclude.

In a related commentary, Dr. David S. H. Bell, from the University of Alabama at Birmingham, notes that even though sulfonylureas are still a popular treatment for diabetes, he believes that they should be relegated to third-line therapy, which is consistent with recently published guidelines.

SOURCE: Canadian Medical Association Journal, January 17, 2006.